Venous Valve Prosthesis with Dynamic Flow-Responsive Leaflets
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Solution Overview
Problem
Existing venous valve prostheses are complex to fabricate, prone to thrombosis, and difficult to deliver percutaneously, especially to small veins, while native venous valves are challenging to reconstruct and often fail, leading to varicose veins and chronic venous insufficiency.
Innovation Solution
A venous valve prosthesis with a self-expanding frame and prosthetic valve that transitions between closed and open configurations based on blood flow direction, preventing thrombosis by allowing continuous blood movement past the prosthesis and anchoring within the vein, thereby reducing retrograde flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin leaflet design is used to replicate native venous valves, then the prosthesis can prevent retrograde blood flow, but it is complicated to fabricate and deliver percutaneously
Solution Approach 1:
The prosthetic valve is divided into multiple discrete components: a self-expanding frame with multiple struts, a separate prosthetic valve component, and a delivery system with sheath and pusher. This segmentation allows each component to be optimized independently and simplifies the delivery process through sequential deployment
Solution Approach 2:
The prosthetic valve and frame are nested within a delivery sheath in a compressed state, allowing percutaneous delivery through small access points. Upon deployment, the self-expanding frame expands outward while the prosthetic valve is positioned and secured, transforming from a compact deliverable state to a functional implanted state
2Reliability
If known prosthetic venous valves are implemented, then valve function is achieved, but they tend to form thrombosis soon after implementation
Solution Approach 1:
The prosthetic valve is designed to be dynamic rather than static, opening in response to antegrade blood flow and closing in response to retrograde pressure. This dynamic behavior replicates native valve physiology and maintains natural blood flow patterns, preventing thrombosis formation
Solution Approach 2:
The valve utilizes pressure gradient changes in the blood flow to transition between open and closed states. During antegrade flow, the pressure gradient keeps the valve open; during retrograde flow, the pressure gradient reverses and closes the valve, maintaining physiological flow conditions that prevent thrombosis
3Reliability
If venous valves are reconstructed surgically, then valve function can be restored, but the procedure is complicated
Solution Approach 1:
The self-expanding frame automatically expands to its functional configuration upon deployment without requiring additional surgical manipulation. The frame's elastic memory allows it to self-assemble into the correct position and shape, reducing surgical complexity and procedure time
Solution Approach 2:
A delivery system with sheath and pusher acts as an intermediary mechanism to guide and deploy the prosthetic valve through percutaneous access. This intermediary system simplifies the surgical procedure by enabling minimally invasive delivery compared to traditional open surgical reconstruction
4Reliability
If a prosthesis is designed to prevent retrograde flow by contacting the vein wall, then valve function is achieved, but it may obstruct continuous blood movement and promote thrombosis
Solution Approach 1:
The prosthetic valve dynamically transitions between closed (contacting vein wall to prevent retrograde flow) and open (allowing antegrade flow) states based on blood flow direction. This dynamic behavior ensures continuous blood movement during normal circulation while preventing retrograde flow during reversal
Solution Approach 2:
The valve responds to changes in blood flow pressure gradients by transitioning between open and closed configurations. During antegrade flow, the pressure gradient maintains the valve in an open state allowing continuous blood movement; during retrograde flow, the pressure gradient closes the valve to prevent backflow
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The venous valve prosthesis is easier to fabricate and deliver, reduces thrombosis formation, and effectively prevents retrograde blood flow, improving venous function and reducing the risk of varicose veins and chronic insufficiency.
Implementation Method 1
The frame may be a self-expanding frame such that the frame exerts a radially outward force on the prosthesis
Implementation Method 2
The radially outward force is partially overcome by antegrade blood flow to enable the portion of the outer wall of the prosthetic valve to partially collapse inward in response to antegrade blood flow through the vein
Data Source
AI summary
A venous valve prosthesis includes a frame and a prosthetic valve coupled to the frame. With the venous valve prosthesis implanted in a vein, the prosthetic valve includes a closed configuration wherein an outer surface of the prosthetic valve is in contact with a wall of the vein around a circumference of the prosthetic valve to prevent blood from flowing past the prosthetic valve between the wall of the vein and the outer surface of the prosthetic valve. The prosthetic valve is configured to move to an open configuration such that at least a portion of an outer wall of the prosthetic valve partially collapses away from the wall of the vein in response to antegrade blood flow through the vein to enable blood flow between the outer surface of the prosthetic valve and the wall of the vein.